Aqueous adhesive for inorganic materials

ABSTRACT

To provide an aqueous adhesive for an inorganic material with excellent adhesiveness to the inorganic material. An adhesive improver (J) for an aqueous adhesive for an inorganic material including a copolymer (A) containing an unsaturated (poly) carboxylic acid (anhydride) (a1) and a (meth) acrylic acid alkyl (2 to 30 alkyl carbon atoms) ester (a2) as a constituent monomer; and an aqueous adhesive for an inorganic material (X) including the adhesive improver (J), saccharide (B), a polycarboxylic acid (C) having 4 to 24 carbon atoms and water.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of International Patent ApplicationNo. PCT/JP2019/016196 filed on Apr. 15, 2019, which claims priority toJapanese Patent Application No. 2018-079769 filed on Apr. 18, 2018, theentire disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an aqueous adhesive for an inorganicmaterial.

BACKGROUND ART

Conventionally, heat resistant inorganic fiber stacks are composed frominorganic fiber such as glass wool, rock wool, or the like; are preparedby molding the inorganic fiber, after a binder is attached thereto forthe purpose of adhesion, in a matted form or the like by a mechanicalmeans; and are used widely as insulating material for buildings andvarious apparatus, and the like. As the binder, an aqueous bindercomposed of a phenol resin which is a condensate of a phenol compoundand formaldehyde has been widely used conventionally, but the bindernormally contains formaldehyde, and there is the problem thatformaldehyde is released into the environment from a stack in which itis used, and therefore improved binders that does not containformaldehyde have been proposed (refer to PTL1 and PTL2, for example).

CITATION LIST Patent Literature

PTL1: Japanese Patent Laid-Open No. 2007-9206

PTL2: Japanese Patent Laid-Open No. 2005-68399

SUMMARY OF INVENTION Technical Problem

However, the binder of the above PTL 1 is a composition comprising anaqueous solution of an oligomer or cooligomer of an ethylenicallyunsaturated carboxylic acid and polyol, which has a number-averagemolecular weight of 300 to 900, but the adhesiveness of the binder isnot sufficient.

Further, the binder of the above PTL 2 consists of a polyacid containingat least two carboxylic acid groups, an acid anhydride group or a saltthereof, and an emulsion polymer having a polyol containing at least twohydroxyl groups and an ethylenically unsaturated acrylic monomercontaining an alkyl group having 5 or more carbon atoms as a copolymerunit. However, the spraying performance of the binder is decreasedbecause the emulsion polymer is contained and thus there is a problem ofthe insufficient adhesiveness.

The purpose of the present invention is to solve the above problem andto provide an aqueous adhesive for an inorganic material with excellentadhesiveness to the inorganic material.

Solution to Problem

The inventors came to the present invention as the result of studyinghow to achieve the foregoing objective. Specifically, the presentinvention is an adhesive improver (J) for an aqueous adhesive for aninorganic material comprising a copolymer (A) containing an unsaturated(poly) carboxylic acid (anhydride) (a1) and a (meth) acrylic acid alkyl(2 to 30 alkyl carbon atoms) ester (a2) as a constituent monomer; and anaqueous adhesive for an inorganic material (X) comprising the adhesiveimprover (J), saccharide (B), a polycarboxylic acid (C) having 4 to 24carbon atoms and water.

Advantageous Effects of Invention

The adhesive improver (J) for an aqueous adhesive for an inorganicmaterial of the present invention achieves the following effects.

(1) Adding advantageous adhesiveness to an aqueous adhesive for aninorganic material.

(2) Adding advantageous water resistance to an adhered inorganicmaterial (in particular, an inorganic fiber stack).

(3) Adding advantageous rigidity to an adhered inorganic material (inparticular, an inorganic fiber stack).

DESCRIPTION OF EMBODIMENTS Unsaturated (poly) carboxylic acid(anhydride) (a1)

The unsaturated (poly) carboxylic acid (anhydride) (a1) in the presentinvention is a (poly) carboxylic acid (anhydride) having 3 to 30 carbonatoms [hereinafter, abbreviated as C in places] having one polymerizableunsaturated group. Note that in the present invention, unsaturated(poly) carboxylic acid (anhydride) means unsaturated monocarboxylicacid, unsaturated polycarboxylic acid and/or unsaturated polycarboxylicacid anhydride.

In the (a1), the unsaturated monocarboxylic acid may be aliphatic (3 to24 C atoms, for example, acrylic acid, methacrylic acid, α-ethyl acrylicacid, crotonic acid, isocrotonic acid) or alicyclic containing (6 to 24C atoms, for example, cyclohexene carboxylic acid); the unsaturated poly(2 to 3 or more) carboxylic acid (anhydride) may be unsaturateddicarboxylic acid (anhydride) [aliphatic dicarboxylic acid (anhydride)(4 to 24 C atoms, for example, maleic acid, fumaric acid, itaconic acid,citraconic acid, mesaconic acid, and anhydrides thereof), alicycliccontaining dicarboxylic acid (anhydride) (8 to 24 C atoms, for example,cyclohexene dicarboxylic acid, cycloheptene dicarboxylic acid,bicycloheptene dicarboxylic acid, methyl tetrahydrophthalic acid, andanhydrides thereof)]. (a1) may be either one type alone or a combinationof two or more types.

From the perspective of adhesiveness of the inorganic material, in theabove (a1), acrylic acid, methacrylic acid, maleic acid, and maleicanhydride are advantageous, and more advantageous is acrylic acid andmethacrylic acid, and particularly advantageous is acrylic acid.

(meth) acrylic acid alkyl (2 to 30 alkyl Carbon Atoms) ester (a2)

The (meth) acrylic acid alkyl (2 to 30 alkyl carbon atoms) ester (a2) inthe present invention may be, for example, ethyl (meth) acrylate, butyl(meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate,isodecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth)acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate,octadecyl (meth) acrylate, eicosyl (meth) acrylate, triacontyl (meth)acrylate, 2-octyl nonyl (meth) acrylate, 1-hexyl tridecyl (meth)acrylate, 2-butylheptadecyl (meth) acrylate, 1-octylpentadecyl (meth)acrylate, 2-decyltetradecyl (meth) acrylate, or (meth) acrylate2-dodecylhexadecyl.

From the perspective of water resistance and adhesiveness of theinorganic material, in the above (a2), the alkyl having 2 to 28 C atomsis advantageous, and more advantageous is that the alkyl having 4 to 20atoms, and particularly advantageous is that the alkyl ester is abranched alkyl ester, or a combination of a linear alkyl ester and abranched alkyl ester.

Copolymer (A)

The copolymer (A) in the present invention is a copolymer [hereinafterdescribed as (co) polymer] containing the unsaturated (poly) carboxylicacid (anhydride) (a1) and a (meth) acrylic acid alkyl (2 to 30 alkylcarbon atoms) ester as constituent monomers [hereinafter described asconstituent units].

From the perspective of water resistance and adhesiveness of theinorganic material, a weight ratio [(a1)/(a2)] of a monomer thatconstitutes the (A) is advantageously 40/60 to 99/1, and moreadvantageously 60/40 to 98/2, and particularly advantageously 70/30 to97/3.

In the (A), in so far as the effect of the present invention is notinhibited, an unsaturated monomer (x) other than the foregoing (a1) and(a2) monomers may be a copolymer to be a constituent monomer.

The unsaturated monomer (x) may be hydroxyalkyl (1-5 C atoms) (meth)acrylate, (meth) acrylamide, styrene, allylamine, (meth) acrylonitrile.

Based on the total weight of (a1) and (a2), the foregoing (x) is 20 wt.% or less advantageously, and more advantageously 5 wt. % or less, andparticularly advantageously 1 wt. % or less.

From the perspective of adhesiveness and handling, the weight-averagemolecular weight of (co) polymer (A) [hereinafter abbreviated to Mw.Measurement is by a later-described gel permeation chromatography (GPC)method.], is advantageously 6,000 to 100,000, and more advantageously8,000 to 75,000, and particularly advantageously 10,000 to 50,000.

Mw and the number average molecular weight (Mn) GPC measurementconditions in the present invention are as follows.

GPC Measurement Conditions

[1] Apparatus: gel permeation chromatography

-   -   [Model number “HLC-8120 GPC”, made by Tosoh Corporation]

[2] Columns: “TSK gel G6000 PWxl”, “TSK gel G3000 PWxl”

-   -   [Both made by Tosoh Corporation] are connected in series.

[3] Eluent: 0.5 wt. % of sodium acetate dissolved inmethanol/water=30/70 (volume ratio).

[4] Reference substance: polyethyleneglycol (hereinafter abbreviated asPEG)

[5] Injection conditions: sample concentration 0.25 wt. % by weight,column temperature 40° C.

From the perspective of productivity, the (co) polymer (A) can beprepared by a publicly known solution polymerization method, awater-containing solution polymerization method is advantageous. As awater content rate, using 40 wt. % or more of water in relation to thetotal solvent amount used is advantageous, and making the entire amountof solvent to be used be water is advantageous.

In a case where an organic solvent is used, it may be either dissolvedin water after desolvation after polymerization or may be used as iswithout desolvation. Organic solvents that can be used alone or togetherwith water are aqueous solvents (solubility in water at 25° C. is 10g/100 g or more water), for example ketone (such as acetone,methylethylketone (hereinafter abbreviated as MEK), diethyl ketone, andthe like), alcohols (methanol, ethanol, isopropanol, and the like), andfrom the perspective of productivity, acetone, MEK, and isopropanol areadvantageous. For the organic solvent, it is possible to use one type or2 or more types.

This (A) is obtained, for example, as a solution (from an industrialperspective, an aqueous solution is advantageous), and from theperspective of productivity and handleability when preparing an aqueousadhesive in post-processing, the content (wt. %) of (A) in the solutionis advantageously 5 to 80%, is more advantageously 10 to 70%, and isparticularly advantageously 20 to 60%.

From the perspective of productivity and control of the molecular weightof (A), the polymerization temperature when preparing the foregoing (A)is advantageously 0 to 200° C., and more advantageously 40 to 150° C.

From the perspective of reduction in remaining monomer content in theproduct and productivity, the polymerization time is advantageously 1 to10 hours, and more preferably 2 to 8 hours.

The end point of the polymerization reaction can be confirmed by theremaining monomer amount. From the perspective of adhesiveness inrelation to an inorganic material, the remaining monomer amount isadvantageously 5% or less based on the weight of (A), and moreadvantageously 3% or less. The remaining monomer amount can be measuredby a gas chromatography method.

Adhesive Improver (J) for an Aqueous Adhesive for an Inorganic Material

The adhesive improver (J) for an aqueous adhesive for an inorganicmaterial of the present invention contains the (co) polymer (A). From anindustrial and handling perspective, the weight of (A) which is based onthe weight of (J) is advantageously 10 to 80 wt. %, and is moreadvantageously 20 to 60 wt. %.

This adhesive improver (J) is used favorably as an adhesive improver forlater-described aqueous adhesive for an inorganic material (X).

Saccharide (B)

The saccharide (B) in the present invention, for example, may be a sugaralcohol (xylitol, sorbitol, mannitol, maltitol, lactitol, erythritol, orthe like), or a (poly) saccharide (dextrin or the like).

The above-described (B), from the perspective of adhesiveness isadvantageously a sugar alcohol.

Note that for the above-described (B), it is possible to use one type ora combination of 2 or more types.

Polycarboxylic Acid (C) having 4 to 24 Carbon Atoms

The polycarboxylic acid (C) in the present invention, for example, maybe something having 4 to 24 carbon atoms [hereinafter may be abbreviatedto C], maleic acid, fumaric acid, itaconic acid, citraconic acid,mesaconic acid, cyclohexene dicarboxylic acid, cycloheptene dicarboxylicacid, bicycloheptene dicarboxylic acid, methyl tetrahydrophthalic acid,citric acid, malic acid, trimellitic acid and their anhydrides.

From the perspective of adhesiveness, the above-described polycarboxylicacid (C) is advantageously trivalent carboxylic acid and moreadvantageously citric acid.

Note that for the polycarboxylic acid (C), it is possible to use onetype alone or to use 2 or more types.

Aqueous Adhesive for an Inorganic Material (X)

The aqueous adhesive for an inorganic material (X) of the presentinvention contains the adhesive improver (J), the saccharide (B), thepolycarboxylic acid (C), and water.

The aqueous adhesive for an inorganic material (X) can be used as anaqueous adhesive for an inorganic material (glass, ceramics, metal), andin particular can be used favorably as an aqueous adhesive (a so-calledaqueous binder for inorganic fiber) for an inorganic fiber such as glasswool, rock wool, or the like.

Based on the total weight of the saccharide (B) and the polycarboxylicacid (C), from the perspective of rigidity and adhesiveness, the weightof the (co) polymer (A) is advantageously 1 to 20 wt. %, moreadvantageously 3 to 15 wt. %, and particularly advantageously 5 to 10wt. %.

The weight ratio [(B)/(C)] between the foregoing saccharide (B) and thepolycarboxylic acid (C), from the perspective of adhesiveness, isadvantageously 25/75 to 75/25, more advantageously 30/70 to 70/30, andparticularly advantageously 35/65 to 65/35.

Based on the weight of the aqueous adhesive (X), the total weight of (A)and (B) and (C), from the perspective of handleability, isadvantageously 10 to 70 wt. %, more advantageously 20 to 60 wt. %, andparticularly advantageously 30 to 50 wt. %.

In the aqueous adhesive for an inorganic material (X) of the presentinvention, as necessary, in so far as the effect of the presentinvention is not inhibited, a curing accelerator (sodium hypophosphite,ammonia, diethylenetriamine, or the like) may be contained. The curingaccelerator, based on the total weight of (A) and (B) and (C), from theperspective of adhesiveness, is advantageously 1 to 15 wt. %, moreadvantageously 2 to 10 wt. %, and particularly advantageously 3 to 5 wt.%.

The method for fabricating the aqueous adhesive for an inorganicmaterial (X) of the present invention is not particularly limited if itis a method by which it is possible to mix and disperse the adhesiveimprover (J) containing the (co) polymer (A), the saccharide (B), thepolycarboxylic acid (C), water, and a curing accelerator added asnecessary. The mixing time is, for example, 30 minutes to 3 hours, anduniform mixing of the aqueous adhesive for an inorganic material (X) canbe confirmed by visual observation.

Note that the above-described (J), (B), (C), and the curing acceleratormay each be mixed in a solution form, advantageously an aqueous solutionform, to obtain the aqueous adhesive (X).

Because the aqueous adhesive for an inorganic material (X) of thepresent invention is not something that consists of the conventionalphenol resin which is a condensate of phenol compound and formaldehyde,it does not contain formaldehyde. Also, the aqueous adhesive for aninorganic material (X) is significantly advantageous in inorganicmaterial adhesiveness, adhered inorganic material water resistance, andrigidity, as evaluated by the methods described below.

The aqueous adhesive for an inorganic material (X) of the presentinvention is favorably used as an aqueous adhesive for inorganic fiberwhich is a particularly heat-resistant stack material.

The inorganic fiber may be a glass fiber, a slag fiber, rock wool,asbestos, metal fiber, or the like.

Adhered Inorganic Material

The adhered inorganic material of the present invention is something inwhich an inorganic material is bonded by a cured product of the aqueousadhesive for an inorganic material (X). Note that in a case where theinorganic material is an inorganic fiber, advantageously is alater-described inorganic fiber stack.

The cured product adhering amount of the aqueous adhesive (X) based onthe weight of the inorganic material, from the perspective of inorganicmaterial adhesiveness and adhered inorganic material rigidity and waterresistance, is advantageously 0.5 to 30 wt. %, more advantageously 1 to20 wt. %, and particularly advantageously 2 to 15%.

Inorganic Fiber Stack

The inorganic fiber stack is an inorganic fiber stack in which theaqueous adhesive (X) cured product is attached to an inorganic fiberstack. Specifically, it is obtained by, for example, attaching theaqueous adhesive (X) to inorganic fiber, and thereafter layering that toproduce a stack, and heating and molding it, or layering the inorganicfiber or a strand (fiber bundle) thereof to produce a stack, spraying anaqueous adhesive (X) thereon to attach it thereto, and heating andmolding.

The method of attaching the aqueous adhesive (X) to the inorganic fiberor a stack thereof may be, for example, a known method such as airspraying or airless spraying, padding, impregnation, roll coating,curtain coating, beater deposition, coagulation, or the like.

The cured product adhesion amount of the aqueous adhesive (X) which isbased on the weight of the inorganic fibers (inorganic fiber stack) thatconstitute the inorganic fiber stack, from the perspective of inorganicfiber adhesiveness, smoothness of the stack front surface, and rigidityand water resistance of the stack, is advantageously 0.5 to 30 wt. %,more advantageously 1 to 20 wt. %, and particularly advantageously 2 to15%.

At the time of preparation of an adhered inorganic material(advantageously an inorganic fiber stack) of the present invention,after an appropriate amount of the aqueous adhesive (X) is attached toan inorganic material, for example, (advantageously an inorganic fiber),it is heated and cured.

The heating temperature, from the perspective of stack adhesiveness andwater resistance, and suppression of coloration of the stack, and froman industrial perspective, is advantageously 100 to 400° C., and moreadvantageously 200 to 350° C.

The heating time, from the perspective of reaction rate and suppressionof coloration of the adhered inorganic material (advantageouslyinorganic fiber stack), is advantageously 2 to 90 minutes, and moreadvantageously 5 to 40 minutes.

The adhesive improver (J) and the aqueous adhesive for an inorganicmaterial (X) of the present invention are advantageous in adhesivenessin relation to an inorganic material (advantageously an inorganicfiber), and can provide advantageous rigidity and water resistance in anadhered inorganic material (advantageously an inorganic fiber stack).This is assumed to be due the fact that, by the configurations of (J)and (X), during curing, an adhesive melt tends to collect efficiently atthe inorganic material adhesion surface, and at the intersection of theinorganic fibers in the case of inorganic fibers, and curing proceedsefficiently at the adhesion surface and the intersection points, andthat the cured product has advantageous resin physical properties.

EXAMPLE

Hereinafter, the present invention will be described in detail withembodiments, but the present invention is not limited thereto. In thefollowing, parts and % respectively indicate parts by weight and wt. %.

Example 1

435 parts of isopropanol [solvent] were charged in an autoclave,nitrogen bubbling was performed while stirring to carry out nitrogensubstitution in the autoclave (gaseous oxygen concentration of 500 ppmor less). After increasing the temperature to 82° C. while blowing innitrogen, a solution [initiator] in which 0 parts 3-mercaptopropionicacid [chain transfer agent] and 4.5 parts of 2,2′-azobis(2-methylbutyronitrile) are dissolved in 100 parts isopropanol and amixed solution of 282 parts of acrylic acid (a1-1) and 7.9 parts ofacrylic acid 2-ethylhexyl (a2-5) were dripped simultaneously for 2hours, and a polymerization reaction was conducted by further mixing for2 hours at 82° C.

After that, the isopropanol in the solution was desolvated, water wasadded so that nonvolatile matter becomes 40%, and an adhesive improver(J-1) [aqueous solution] for an aqueous adhesive for an inorganicmaterial containing (co) polymer (A-1) was obtained. Note that (A-1) hadan Mw of 12, 000 and an acid value of 760.

Examples 2 to 11, Comparative Example 1

In addition to following the reaction composition (parts) in Table 1 inthe example 1, adhesive improvers (J-2) to (J-11) and (comparative J-1)were obtained similarly to in the example 1. The results are indicatedin Table 1.

Preparation Example 1

46.7 parts of water was charged in a container, and while stirring, 53.3parts Malbit [made by B food science Co., Ltd, 75% sugar alcoholsolution] was charged over 1 hour. Furthermore, it was stirred for 1hour, and a 40% aqueous solution of (B-1) was obtained.

Preparation Example 3

42.9 parts of water was charged in a container, and while stirring, 57.1parts Sweet G2 [made by B food science Co., Ltd, 70% sugar alcoholsolution] was charged over 1 hour. Furthermore, it was stirred for 1hour, and a 40% aqueous solution of (B-3) was obtained.

Examples 21 to 36, Comparative Example 21

In accordance with the compound compositions (parts) indicated in Table2, they were charged in the container, blending was performed, and eachaqueous adhesive for an inorganic material (X) was thereby prepared.Using the obtained aqueous adhesive (X), a test piece of inorganic fiberstack was produced according to the following overview, and evaluationwas performed by the respective methods described below. The results areindicated in Table 2.

Production of Inorganic Fiber Stack

A glass fiber stack whose height x width x thickness were 30 cm×30 cm×2cm and whose density was 0.035 g/cm³ was placed in a flat-shaped moldsubjected to release processing whose height×width×depth were 30 cm×30cm×5 cm.

Next, an aqueous adhesive for which the cured product adhering amount is15% in relation to the weight of the stack was sprayed uniformly on thestack using an air spray. After that, heat processing (drying, curing)was performed for 50 minutes in a circulating dryer at 210° C., and thestack (S-1) whose thickness was approximately 2 cm and whose density was0.040 g/cm³ was obtained. Similarly, a total of 5 stacks (S-1) wereproduced.

(1) Evaluation of Adhesiveness

From each stack (S-1), 5 test pieces whose length x width x thicknesswere 10 cm×1.5 cm×2 cm were cut out. Using Autograph [Model number“AGS-500D”, made by Shimazu Corporation], tensile strength was measuredin conformance with “7.4 Tensile Strength” of JISR3420 “Glass FiberGeneral Test Methods”, and the average values for the 5 test pieces wereused to evaluate adhesiveness by the following criteria.

Evaluation Criteria

⋆: 500N/m² or more

⊚: 450N/m² or more and less than 500N/m²

○: 400N/m² or more and less than 450N/m²

Δ: 300N/m² or more and less than 400N/m²

x: less than 300N/m²

(2) Evaluation of Water Resistance

From each stack (S-1), 5 test pieces whose length x width x thicknesswere 10 cm×1.5 cm×2 cm were cut out. These were soaked for 10 minutes intap water at 25° C. Then they were extracted, allowed to stand on asieve having openings of 400 μm for 60 minutes at 30° C. and 40% RH.

The tensile strength of the test pieces after the water resistance testwas measured similarly to in the foregoing (1), the strength after thewater resistance test×100/the intensities in the foregoing (1) (units:%) was calculated, and water resistance was evaluated by the followingevaluation criteria.

Evaluation Criteria

⋆: 90% or more

⊚: 80% or more and less than 90%

○: 70% or more and less than 80%

Δ: 60% or more and less than 70%

x: less than 60%

(3) Evaluation of Rigidity

From each stack (S-1), 5 test pieces whose length x width x thicknesswere 30 cm×1 cm×0.5 cm were cut out.

The test piece was placed on a base whose distance between supportingpoints is 25 cm, a deflection ratio of the test pieces at 25° C. wasmeasured, and for the average value of the 5 test pieces, the rigiditywas evaluated by the following criteria.

The deflection ratio (%) of the test piece=deflection (mm)×100/250

Evaluation Criteria

⋆: A deflection ratio of less than 1.0%

⊚: A deflection ratio of 1.0% or more and less than 2.0%

○: A deflection ratio of 2.0% or more and less than 3.0%

Δ: A deflection ratio of 3.0% or more and less than 5.0%

x: A deflection ratio of 5.0% or more

Example Comparative Example  1  2  3  4  5  6  7  8  9  10  11

Adheaive improver  J-1  J-2  J-3  J-4  J-5  J-6  J-7  J-8  J-9  J-10 J-11  CJ-1 (co) polymer (A) A-1 A-2 A-3 A-4 A-5 A-6 A-7 A-8 A-9 A-10A-11 CA-1 Reaction composition (parts) Solvent water  30 50 Isopropanol

270

380

320 280 300

Chain

 agent 3-mercaptopropionic acid

Initiator 2,2′-azobis (2,4-dimethyl-valeronitrile)  0.25

 0.1 2,2′-azobis (2-methylbutyronitrile)

 0.14

Isopropanol water 100

 40

Unsaturated (poly)

 acid Acrylic acid (a1-1) 282

Methacrylic acid (a1-2) 100 (

) (

) Maleic anhydride (a1-3)

(

) acrylic acid

Butyl acrylate (a2-1)

Ethyl acrylate (a2-2) 12 100 2-ethylhexyl (meth)

acrylate (a2-3) Isodecyl (meth) acrylate (a2-4)  112-ethylhexy-lacrylate (a2-5)

Octadecyl acrylate (a2-6)

Hexadecyl acrylate (a2-7) 12

Acrylamide 55.0 Property of

 12.000

18.000

11.000

21.000 12.000 (co) polymer Acid value

580 756

Weight ratio [(a1)/(a2)]

indicates data missing or illegible when filed

Comparative Example Example 21 22 23 24 25 26 27 28 29 30 31 32 33 34 3536 21 Aqueous adhesive for an inorganic material X-1 X-2 X-3 X-4 X-5 X-6X-7 X-8 X-9 X-10 X-11 X-12 X-13 X-14 X-15 x-16 CX-1 Compound compositionAdhesive J-1 2.5 3 2 4 2.5 (parts) improver J-2 2.5 (J) J-3 5 J-4 2.5 10J-5 3.5 J-6 1 J-7 2.5 J-8 2.5 J-9 3 J-10 1 J-11 3 CJ-1 5 Saccharide (B)40% aqueous solution of (B-1) 20 22 16 20 16 22 16 20 22 40% aqueoussolution of sorbitol (B-20) 30 25 40% aqueous solution of (B-3) 16 1640% aqueous solution of

 (B-4) 32 22 40% aqueous solution of sucrose (B-5) 25 40% aqueoussolution of dextrin (B-6) 25 Polycarboxylic 40% aqueous solution ofcitric acid 28 26 20 32 20 28 32 26 32 30 32 28 26 acid (C) (C-1) 40%aqueous solution of

 acid (C-2) 24 26 40% aqueous solution of

 acid (C-3) 25 25 40% aqueous solution of

 acid (C-4) 45

 accelerator Sodium hypophosphite 2 5 3 2 Water 50 50 50 50 50 50 50 5050 50 50 50 50 50 50 50 50 Weight of (A) based on the total weight of(B) and (c)

5 6 10 5 20 8 2 5 5 4 7 4 6 2 6 — Evaluation Adhesiveness ⋆ ⊚ ◯ ◯ ⊚ ◯ ⊚◯ ◯ ⊚ ⋆ ◯ ⊚ ⊚ ⊚ ◯ ϰ Results Water resistance ⊚ ⋆ ⊚ ⋆ ⋆ ⋆ ⊚ ⊚ ⋆ ⋆ ◯ ⊚ ◯ ⋆⋆ ⋆ Δ Rigidity ◯ ◯ ⊚ ⊚ ⋆ ⊚ ◯ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ ◯ ◯ ⊚ ϰ

indicates data missing or illegible when filed

From the results of Tables 1 and 2, it can be seen that the adhesiveimprover (J) for the aqueous adhesive for an inorganic material of thepresent invention, compared to the comparative example, addsadvantageous adhesiveness of the inorganic material (in particular theinorganic fiber) to the aqueous adhesive for an inorganic material, andfurther adds advantageous water resistance and rigidity to the adheredinorganic material (in particular inorganic fiber stack).

The present invention is not limited to the above embodiments andvarious changes and modifications can be made within the spirit andscope of the present invention. Therefore, to apprise the public of thescope of the present invention, the following claims are made.

USABILITY IN INDUSTRY

The adhesive improver (J) and the aqueous adhesive for an inorganicmaterial (X) of the present invention is suitable for adhering inorganicmaterial (in particular, a glass fiber which is an inorganic fiber whichis a heat-resistant stack material), and since an adhered inorganicmaterial in which the aqueous adhesive is used (in particular, aninorganic fiber stack) can be applied in a wide variety of fields asvarious adhered inorganic materials, and in particular as a heatinsulating material, a heat retention material, and a sound absorbingmaterial for buildings and various apparatuses, it is highly useful.

What is claimed is:
 1. An adhesive improver (J) for an aqueous adhesivefor an inorganic material comprising a copolymer (A) containing anunsaturated (poly) carboxylic acid (anhydride) (a1) and a (meth) acrylicacid alkyl (2 to 30 alkyl carbon atoms) ester (a2) as a constituentmonomer.
 2. The adhesive improver of claim 1, wherein a weight ratio[(a1)/(a2)] of the (a1) and (a2) in a constituent monomer is 40/60 to99/1.
 3. The adhesive improver of claim 1, wherein the (a1) is oneselected from the group consisting of an acrylic acid, a methacrylicacid, a maleic acid and a maleic anhydride.
 4. The adhesive improver ofclaim 1, wherein a weight-average molecular weight of the copolymer (A)is 6,000 to 100,000.
 5. An aqueous adhesive for an inorganic material(X) comprising the adhesive improver (J) of claim 1, saccharide (B), apolycarboxylic acid (C) of 4 to 24 carbon atoms and water.
 6. Theaqueous adhesive of claim 5, wherein a weight ratio [(B)/(C)] of thesaccharide (B) and polycarboxylic acid (C) is 25/75 to 75/25.
 7. Theaqueous adhesive of claim 5, wherein the weight of the copolymer (A) is1 to 20 wt. % based on the total weight of the saccharide (B) andpolycarboxylic acid (C).
 8. An adhesive article of an inorganic materialbonded with a cured material of the aqueous adhesive (X) of claim 5.